I have both 45 and 10mm Glocks. I bought a few of the Kriss kits to convert to 30-round mags. Doesn't work with the 10mm mags. There are some YouTube videos of some guys who finagled and got them to work, but I wouldn't trust them for anything other than range toys.
I've never felt "undergunned" or inadequate carrying 15+1 of 230-grain loads in the woods, which is the only time I carry my 20.